Aight so ik the thing about how the music "It's Raining Somewhere Else" from the Undertale soundtrack is basically a slowed down version of Sans's theme song and ik how ppl think it's to show how lazy Sans is and all, but I kinda just think of it differently

It's raining somewhere else only plays when you're having an emotional moment with Sans. He's revealing something about himself. Like when he's having dinner with you before you leave and kind of wants you to stay or when you find Sans' hidden lab. Sans theme song plays when you're talking to him and he's still joking around.

I think his theme song was meant to show how Sans is around others. He's always pretending to be happy and just this chilled jokester. But it's raining somewhere else basically shows who he really is. An upset, depressed character hiding all his pain.

I think maybe that's what Toby was trying to do with the music. Not show how lazy Sans is, but how much he hides for the sake of others' happiness. 

I think too much about these ;-;